tv_xiaoyouxi/games/symdsb/frameworks/cocos2d-html5/CCVertex.js

/****************************************************************************
 Copyright (c) 2008-2010 Ricardo Quesada
 Copyright (c) 2011-2012 cocos2d-x.org
 Copyright (c) 2013-2014 Chukong Technologies Inc.
 Copyright (c) 2009      Valentin Milea

 http://www.cocos2d-x.org

 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights
 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 copies of the Software, and to permit persons to whom the Software is
 furnished to do so, subject to the following conditions:

 The above copyright notice and this permission notice shall be included in
 all copies or substantial portions of the Software.

 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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 ****************************************************************************/

/**
 * converts a line to a polygon
 * @param {Float32Array} points
 * @param {Number} stroke
 * @param {Float32Array} vertices
 * @param {Number} offset
 * @param {Number} nuPoints
 */
cc.vertexLineToPolygon = function (points, stroke, vertices, offset, nuPoints) {
    nuPoints += offset;
    if (nuPoints <= 1)
        return;

    stroke *= 0.5;
    var idx;
    var nuPointsMinus = nuPoints - 1;
    for (var i = offset; i < nuPoints; i++) {
        idx = i * 2;
        var p1 = cc.p(points[i * 2], points[i * 2 + 1]);
        var perpVector;

        if (i === 0)
            perpVector = cc.pPerp(cc.pNormalize(cc.pSub(p1, cc.p(points[(i + 1) * 2], points[(i + 1) * 2 + 1]))));
        else if (i === nuPointsMinus)
            perpVector = cc.pPerp(cc.pNormalize(cc.pSub(cc.p(points[(i - 1) * 2], points[(i - 1) * 2 + 1]), p1)));
        else {
            var p0 = cc.p(points[(i - 1) * 2], points[(i - 1) * 2 + 1]);
            var p2 = cc.p(points[(i + 1) * 2], points[(i + 1) * 2 + 1]);

            var p2p1 = cc.pNormalize(cc.pSub(p2, p1));
            var p0p1 = cc.pNormalize(cc.pSub(p0, p1));

            // Calculate angle between vectors
            var angle = Math.acos(cc.pDot(p2p1, p0p1));

            if (angle < cc.degreesToRadians(70))
                perpVector = cc.pPerp(cc.pNormalize(cc.pMidpoint(p2p1, p0p1)));
            else if (angle < cc.degreesToRadians(170))
                perpVector = cc.pNormalize(cc.pMidpoint(p2p1, p0p1));
            else
                perpVector = cc.pPerp(cc.pNormalize(cc.pSub(p2, p0)));
        }
        perpVector = cc.pMult(perpVector, stroke);

        vertices[idx * 2] = p1.x + perpVector.x;
        vertices[idx * 2 + 1] = p1.y + perpVector.y;
        vertices[(idx + 1) * 2] = p1.x - perpVector.x;
        vertices[(idx + 1) * 2 + 1] = p1.y - perpVector.y;
    }

    // Validate vertexes
    offset = (offset == 0) ? 0 : offset - 1;
    for (i = offset; i < nuPointsMinus; i++) {
        idx = i * 2;
        var idx1 = idx + 2;

        var v1 = cc.vertex2(vertices[idx * 2], vertices[idx * 2 + 1]);
        var v2 = cc.vertex2(vertices[(idx + 1) * 2], vertices[(idx + 1) * 2 + 1]);
        var v3 = cc.vertex2(vertices[idx1 * 2], vertices[idx1 * 2]);
        var v4 = cc.vertex2(vertices[(idx1 + 1) * 2], vertices[(idx1 + 1) * 2 + 1]);

        //BOOL fixVertex = !ccpLineIntersect(ccp(p1.x, p1.y), ccp(p4.x, p4.y), ccp(p2.x, p2.y), ccp(p3.x, p3.y), &s, &t);
        var fixVertexResult = !cc.vertexLineIntersect(v1.x, v1.y, v4.x, v4.y, v2.x, v2.y, v3.x, v3.y);
        if (!fixVertexResult.isSuccess)
            if (fixVertexResult.value < 0.0 || fixVertexResult.value > 1.0)
                fixVertexResult.isSuccess = true;

        if (fixVertexResult.isSuccess) {
            vertices[idx1 * 2] = v4.x;
            vertices[idx1 * 2 + 1] = v4.y;
            vertices[(idx1 + 1) * 2] = v3.x;
            vertices[(idx1 + 1) * 2 + 1] = v3.y;
        }
    }
};

/**
 * returns whether or not the line intersects
 * @param {Number} Ax
 * @param {Number} Ay
 * @param {Number} Bx
 * @param {Number} By
 * @param {Number} Cx
 * @param {Number} Cy
 * @param {Number} Dx
 * @param {Number} Dy
 * @return {Object}
 */
cc.vertexLineIntersect = function (Ax, Ay, Bx, By, Cx, Cy, Dx, Dy) {
    var distAB, theCos, theSin, newX;

    // FAIL: Line undefined
    if ((Ax == Bx && Ay == By) || (Cx == Dx && Cy == Dy))
        return {isSuccess:false, value:0};

    //  Translate system to make A the origin
    Bx -= Ax;
    By -= Ay;
    Cx -= Ax;
    Cy -= Ay;
    Dx -= Ax;
    Dy -= Ay;

    // Length of segment AB
    distAB = Math.sqrt(Bx * Bx + By * By);

    // Rotate the system so that point B is on the positive X axis.
    theCos = Bx / distAB;
    theSin = By / distAB;
    newX = Cx * theCos + Cy * theSin;
    Cy = Cy * theCos - Cx * theSin;
    Cx = newX;
    newX = Dx * theCos + Dy * theSin;
    Dy = Dy * theCos - Dx * theSin;
    Dx = newX;

    // FAIL: Lines are parallel.
    if (Cy == Dy) return {isSuccess:false, value:0};

    // Discover the relative position of the intersection in the line AB
    var t = (Dx + (Cx - Dx) * Dy / (Dy - Cy)) / distAB;

    // Success.
    return {isSuccess:true, value:t};
};

/**
 * returns wheter or not polygon defined by vertex list is clockwise
 * @param {Array} verts
 * @return {Boolean}
 */
cc.vertexListIsClockwise = function(verts) {
    for (var i = 0, len = verts.length; i < len; i++) {
        var a = verts[i];
        var b = verts[(i + 1) % len];
        var c = verts[(i + 2) % len];

        if (cc.pCross(cc.pSub(b, a), cc.pSub(c, b)) > 0)
            return false;
    }

    return true;
};